Air conditioning process
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Solution Overview
Problem
Existing air-conditioning systems for stationary heating and cooling face challenges such as high global warming potential, flammability issues with certain refrigerants, and increased energy and costs due to single-phase fluid systems.
Innovation Solution
A process utilizing a vapor compression circuit with a first refrigerant fluid, coupled with a secondary circuit containing a nonflammable second refrigerant fluid, such as hydrofluoroolefin or hydrochlorofluoroolefin, which undergoes a phase change at a low temperature and pressure, facilitating efficient heat transfer while maintaining system safety and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If R-410A refrigerant fluid is used in vapor compression circuits, then high energy efficiency and nonflammability are achieved, but high global warming potential (GWP=2100) results
Solution Approach 1:
The system is divided into two separate circuits: a primary vapor compression circuit using R-410A confined to outdoor units, and a secondary single-phase circuit using alternative refrigerants (R1234yf, R1234ze, R134a) in indoor units. This segmentation allows each circuit to use refrigerants optimized for its specific function and safety requirements, resolving the contradiction between nonflammability and GWP by isolating the high-GWP refrigerant to areas where it poses minimal risk while using low-GWP alternatives where safety is paramount.
Solution Approach 2:
The outdoor unit acts as an intermediary that transfers thermal energy from the R-410A vapor compression circuit to the secondary single-phase refrigerant circuit. This intermediary mechanism allows the system to leverage the high efficiency of R-410A while using safer, lower-GWP refrigerants in the indoor distribution network, effectively mediating between the conflicting requirements of efficiency and safety.
2Object-affected harmful factors
If HFC-32 is used to replace R-410A, then lower GWP (GWP=675) is achieved, but flammability issues arise requiring reduced maximum load per circuit
Solution Approach 1:
The system separates flammable refrigerant usage (HFC-32 in the primary circuit) from occupied spaces by confining it to outdoor units, while using nonflammable alternatives in the secondary indoor circuit. This spatial segmentation allows the system to benefit from HFC-32's lower GWP without compromising safety in sensitive zones, as the flammable refrigerant is isolated from building interiors.
Solution Approach 2:
The outdoor unit serves as an intermediary barrier that prevents direct contact between flammable HFC-32 and indoor environments. By mediating the thermal transfer between the flammable and nonflammable refrigerant circuits, the system enables use of lower-GWP flammable refrigerants while maintaining safety through physical separation and load limitations in the secondary circuit.
3Device complexity
If single-phase fluid is used in secondary circuit, then system simplicity is maintained, but considerable increase in pipework dimensions and higher pumping energy are required
Solution Approach 1:
The system changes the physical parameters of the secondary circuit refrigerant by utilizing phase-change-capable refrigerants (R1234yf, R1234ze, R134a) that can undergo phase transitions at ambient temperatures. This parameter change allows the refrigerant to achieve high heat transfer coefficients through phase change, dramatically reducing the required pipe dimensions and pumping energy compared to single-phase fluids while maintaining system simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution enables efficient and safe air conditioning with reduced facility dimensions, energy costs, and implementation costs, while allowing for the safe circulation of nonflammable refrigerants in sensitive zones without load limitations.
Implementation Method 1
heat exchange between the environment and the first refrigerant fluid
Implementation Method 2
vapor compression circuit
Implementation Method 3
heat exchange between the first and the second refrigerant fluid
Implementation Method 4
undergoes a phase change at a low temperature and pressure
Implementation Method 5
undergoes a phase change at a low temperature and pressure, facilitating efficient heat transfer
Implementation Method 6
undergoes a phase change at a low temperature and pressure, facilitating efficient heat transfer
Implementation Method 7
heat exchange between the second refrigerant fluid and the air to be conditioned
Implementation Method 8
heat exchange between the second refrigerant fluid and the air to be conditioned
Data Source
AI summary
A process for conditioning air, by means of a main circuit, the main circuit being a vapor compression circuit, wherein a first refrigerant circulates, and a secondary circuit with no compressor, wherein a non-flammable second refrigerant including a hydrofluoroolefin and/or a hydrochlorofluoroolefin circulates, the main circuit and the secondary circuit being coupled to one another; the process including a heat exchange between the surroundings and the first refrigerant, a heat exchange between the first and second refrigerants, and a heat exchange between the second refrigerant and the air to be conditioned. Also, an air conditioning plant for implementing the process.